In wells of relatively long penetration into a reservoir, so-called uneven production easily occurs. This implies a dissimilar inflow of reservoir fluid along the well. The situation is mainly due to a pressure drop in the production tubing, and is particularly common in horizontal or near-horizontal wells.
In many of the wells, also in vertical or near-vertical wells, the situation may be due to dissimilar permeability, viscosity or pore pressure in different zones of the well.
The conditions underlying the invention are explained hereinafter with reference to a horizontal well. This does not limit the scope of the invention in any way.
Oftentimes, the inflow into the production tubing is substantially larger at the “heel” of the well than at the “toe” of the well. If this inflow is not controlled, the production will be uneven, which may lead to water or gas coning. This results in new wells having to be drilled in order to be able to recover well fluid from the region at the toe of the well.
It is known to provide chokes, termed ICD's (Inflow Control Devices) in the art, in the inflow path to the production tubing, for example at each pipe joint. The chokes may be adapted individually for the different zones of the well. As the pressure in the reservoir changes, the relative pressure between the different regions of the well changes too, whereby the originally adapted chokes oftentimes do not continue to control the inflow into the well in the desired manner.
GB 2376488 discloses a regulated valve for fluid inflow from a well to a pipe. The valve lacks proper feedback from the well pressure.
WO2008/004875 discloses a disc valve for the same purpose as above that is based on the Bemoulli effect of the flowing fluid against a disk.